Restaurant:
- Make special effects when they're eating like when they open their mouth or when they're chewing.
- If your other friends are also helping you besides the one your annoying, all of you should clap at the same time everytime he/she put something in their mouth.
- Make them laugh when they're drinking, just make sure your not sitting in front of them. Try not to do that when they're eating though, you might end up killing them.
- If your not hungry, don't eat yet and ask "how does the *food item* taste like?" everytime they eat something, even if you asked it before.
- This last one is not recommended if you don't want people to hate you. Talk about something really gross while they're eating.

This works ALL THE TIME in an elevator...
<< make out with an invisible person in the elevator and d oit MAJORLY
<< stick your tongue out and twirl it around as if you're sticking it into their mouth
<< slowly moan in between passionate kisses, "mm... you're good..."
<< to top it all off, yelp and jump up at the same time and pretend to slap an invisible hand away from your private parts

another way is to...
<< get an umbrella and wet it A LOT before entering an elevator
<< open and close it constantly in there in the middle

another way...
<<go into an elevator pretending to yell at someone in a cell phone
<< yell, "I TOLD YOU! I CAN'T SATISFY U ANYMORE COZ I'VE GOT AIDS NOW!"
<< accidentally bump into someone, quickly nod as an apology and yell into cell phone,"AND YOU KNOW THAT IT'S CONTAGIOUS AT PHYSICAL CONTACT! GEEZ! GO CALL A PROSTITUTE OR SOMETHING!"

...
in the mall,
<< walk around on crutches and into a place where there are lots of people and pretend to fall over on your crutches and people'll come to help you
<< just as they are helping you, stand up as if you're fine, pick up your crutches, say "thank you" and run off screaming, "I"VE GOT AIDS!~"
...

Take your hand, put it over their forehead and run your hand down to their chin. Their eyebrows becomes messed up, and they fix it. Then do it over and over until they get pissed and move away from you trying to fix their eyebrow

Sing some annoying song 15+ times.
Flick their forehead, nose, or ear. lmaaoo.
Talk about something they don't care over & over & over again.
Yell about ur personal problems and cuss at them. ( it works for my friend. ;O )
Lock them out of their own house ( if likee u wanna prank them )
Be lazy and tell them to do stuff for you.
Stare at them no matter what, and don't try to laff while staring.
Talk about something really disturbing in front of their face.
Smile smile and smile 24/7 -- if u wanna be plain creepy.
Interrupt them while they say something.
Jump up and down while talking to someone.
On the internet, copy & paste every sentence ur saying.
Fake cry when u don't gte waht u want.
Listen to the same music on the radio 24/7
Say something REEALLLY EXTREMMELY HELLA nice and say just kidding and laff like a freaking lunatic.
Cosplay some annoying anime character.
Laugh at random things / not funny things.
Don't listen to what the say. Just nod ur head and say great idea, absolutely.
Sing in the shower REALLY loud.
SHRIEK when u see a bug, including harmless ones.
Treat someone like a pet. Pat their head say come here boy / girl etc.
Try to steal their favorite food.
Compliment them over and over again.
Lie about how the look and let them know that ur lying.